Inserting at top of richtextbox

问题

Whats wrong with this code? Trying to get my text to insert at the beginning of the textbox rather than at the bottom.

private void execute_Click(object sender, EventArgs e){
  startFinshBox.Text = "Start Time: " + printTime()+"";
  startFinshBox.Text.Insert(0,printTime()+": Retrieving Results...\n");
}

But it will not insert the second line into the rtb. I have tried with startFinishBox.SelectionStart = 0 as well, and it made no difference. Am I missing something else?

Thanks, Psy

回答1:

startFinshBox.Text is a string, which is an immutable type in C#. string.Insert() will return the modified string as a result, but it your code you discard it. To make it work, you have to change the code to:

private void execute_Click(object sender, EventArgs e){
  startFinshBox.Text = "Start Time: " + printTime()+"";
  startFinshBox.Text = startFinshBox.Text.Insert(0,printTime()+": Retrieving Results...\n");
}

回答2:

The SelectionStart property on a TextBox will determine where text will be selected or inserted from.

Use this code to insert code at the start of the text box control:

TextBox.SelectionStart = 0;
TextBox.SelectedText = "Start time: " + printTime();

来源：https://stackoverflow.com/questions/1818875/inserting-at-top-of-richtextbox